See the 'America's Got Talent' Act That Brought Simon Cowell to Tears

In a rare moment on America's Got Talent, judge Simon Cowell showed his vulnerable side after contestant Michael Ketterer brought him to tears by singing James Bay's "Us."

Ketterer, a pediatric nurse living with his wife and six kids in Orange County, California, wowed the judges and the audience with his emotional rendition of the song as well as his backstory. Ketterer and his wife are the parents of six children, including their biological daughter, Sophie, and five sons adopted from foster care.

The AGT quarterfinalist captivated and even earned a standing ovation from the audience Tuesday night when he sang the song's final notes.

The performance seemed to especially resonate with Cowell, who is dad to 4-year-old Eric, bringing him to tears following the performance. Cowell, who leapfrogged Ketterer with a golden buzzer to the live rounds back during auditions, tried to get host Tyra Banks to ask a different judge for feedback, but she persisted that Cowell share his unbridled feelings about Ketterer.

"As a dad, I can't imagine [doing] what you've done, and the fact that you're on this show and you really need this. You're a really, really special guy," Cowell said, his voice cracking with emotion and eyes welled up with tears. "There's' just something about you."

Banks praised Cowell for being open and vulnerable. "That was one of the most beautiful moments I've ever seen from you, that vulnerability and that beauty," she said. "That's what a lot of people don't know about Mr. Cowell, is that he is a big soft papa."

Judge Mel B was choked up as well, taking a second to compose herself before sharing her thoughts. "You're just an incredible person and an incredible human being," the former Spice Girls said. "To do what you've done, adopting all these kids and giving them a life, and then your voice sings such truth and honestly."

Judges Heidi Klum and Howie Mandel also celebrated Ketterer for the message he sends to those watching at home.

"When you sing, you sing with so much heart," Klum said. "And on a side note, we just need more men like you."

"This is not a sob story, this is a happy story," Mandel said. "People should be led and inspired by who you are and how you are."

Ketterer also fought back tears while talking about his family, especially his wife in the audience. "These are my babies, and I have given my entire life to this. I couldn't have done it without my wife, she's one of my greatest supports."

After the show, Cowell told Entertainment Tonight that he was "trying to keep it together" while giving his feedback.

"That normally doesn’t happen to me, but there’s something about Michael," Cowell shared. "[Especially] now that I’ve gotten to know him and what it means to him."

"It’s his sincerity, his kindness and what he’s done to change those kids' lives, and then he puts it all out on the line tonight and I really felt for him, he’s a really special person," Cowell added.

Mandel said that Cowell's reaction wasn't surprising to him, hinting that Cowell's stern reputation may be unfounded.

"I’ve gotten to know Simon personally over the last couple of years and I don’t think people know what kind of a human being and what kind of a father he is and what kind of a friend he is," Mandel told ET. "So many times when he’s just been doing his job and he feels that maybe somebody was hurt by something he said, we go to commercial and he’ll jump up on the stage and give them a hug and make sure they feel good and [give them some] encouragement. He is the first one up there."

"He is the biggest softie, so when you see somebody that is this aspirational, inspirational in what they’re doing -- and [Simon] does a lot of good charitable things for children that aren’t spoken about -- he doesn’t do it for the cameras -- I just thought, 'Oh, my God, this is Simon's lane,' This is exactly what he aspires to be."